I want to plant10 metre leylandii

A tall order John, expensive too. you'll no doubt be aware of the aphid that can destroy the leaves in patches. Having said that I've noticed that it's the closely trimmed ones that are affected, the big open ones seem ok. There are other conifers that don't sercombe to it. Thuja plicata I think is one. They may not grow quite as quick but I doubt there'll be that much difference. I suppose it all depends how old you are, how long you will be resident and how badly you want to obscure the view. Wish I could be more help.

John welcome, you will also need to check on your local council regulations as to hedge heights. Many now stipulate that a hedge can not be higher than 6 foot. As this will be a new planting you don't want to find yourself in the position where you either have to lop 24 foot off the hedge or remove altogether.

Leylandii grow into monsters John, im sure theres a new law where you have to keep them to 6ft, (i could be wrong) but think of all the shade those monsters are going to throw onto your garden :( also they take the moisture out of your soil..
Maybe a new fence would be better and lots of climbers growing up it to take your eye away from that errr View...

what an eye sore! can understand why you would want something BIG and asap

best of luck with your quest

x x x

posted at the same time Moongrower :)

Does this new hedge have to be as high as ten metres, John? In your picture you show existing plantings that appear much higher than the crane due to perspective. Would not one more tallish conifer in the central gap do the business?

I think you are going to regret planting plain Leylandii? As these trees will knit together and form a very high hedge which others may well object to. Rather than plant ugly fast growers I think you would be better to take a longer term view on what to plant to shield you. Also perspective can help as something 1/2 way between can block out a building.

I fully understand your fealings , but I am afraid there is nothing you can do ,people will sell you sutch trees and put them in for you knowing that they will proberly get the job of taking them down, the law states that the limet for leylandi in a boundry can be no higher than seven foot max. so you will waste a lot of money only to have the council telling you cut them down or they will do it and send you the bill,the view is broken up now can you posable plant more things to sofen the out line of the bulding.

Even if it were possible to plant one that size it would probably blow over in the first winter storms unless it was securely tied and anchored to the ground

Agree Cliffo plant more in your garden to hide the new build... which would appear to be gross!

I do understand how you feel as we have had 3 brownfield developements very close to us. We objected but no notice taken. As answers say, put trees at intervals down the garden to shut out the horrible view from the patio and house. We are very overlooked and garden only 50 feet. Foliage on deciduous trees allows privacy May to November, twigs and branches break up the view in winter. People who visit us are surprised how much privacy we have by the placing of our deciduous trees.

You could have a problem under part 8 of the Anti Social Behaviour Act 2003. All evergreen hedges must be no taller than 2 metres in height. The local authority/council can implement a court order to ensure you keep the hedge to that size. This is not local authority law, this is a national (England and Wales) statute. If these are flats going up at the bottom of your garden, the people whose windows are going to be next to your hedge may have something to say about 10 metre high leylandii!! The other downside is that leylandii will suck all of the nutrients out of your soil and you will not be able to grow anything in close proximity to them, even grass. From looking at your picture, you have a very good planting structure already which doesn't expose you too much.